Bacterial gene expression detected in human faeces by reverse transcription-PCR

A method to isolate and specifically detect bacterial messenger RNA (mRNA) in human faeces is presented. The surface layer protein gene slpA of Lactobacillus acidophilus ATCC 4356(T) was chosen as a model system because it is transcribed at a high level to a relatively stable mRNA (Boot et al., 1996, J. Bacteriol. 178, 5388-5394). A simulation of the recovery of bacterial cells in the faecal ecosystem was achieved by spiking faecal homogenates with different levels of L. acidophilus cells and total RNA was isolated using a method based on Macaloid clay. The slpA transcript could be detected by reverse transcription-PCR (RT-PCR) when the L. acidophilus cells comprised more than 0.14% (approximately 2 x 10(7) cells g(-1) faeces) of the complex faecal community.